Struct Impossible

pub struct Impossible<Ok, Error> { /* private fields */ }

Available on crate feature dep_serde only.

Helper type for implementing a Serializer that does not support serializing one of the compound types.

This type cannot be instantiated, but implements every one of the traits corresponding to the Serializer compound types: SerializeSeq, SerializeTuple, SerializeTupleStruct, SerializeTupleVariant, SerializeMap, SerializeStruct, and SerializeStructVariant.

impl Serializer for MySerializer {
    type Ok = ();
    type Error = Error;

    type SerializeSeq = Impossible<(), Error>;
    /* other associated types */

    /// This data format does not support serializing sequences.
    fn serialize_seq(self,
                     len: Option<usize>)
                     -> Result<Self::SerializeSeq, Error> {
        // Given Impossible cannot be instantiated, the only
        // thing we can do here is to return an error.
        Err(...)
    }

    /* other Serializer methods */
}

Trait Implementations

impl<Ok, Error> SerializeMap for Impossible<Ok, Error>

where Error: Error,

type Ok = Ok

Must match the Ok type of our Serializer.

type Error = Error

Must match the Error type of our Serializer.

fn serialize_key<T>(&mut self, key: &T) -> Result<(), Error>

where T: Serialize + ?Sized,

Serialize a map key.

fn serialize_value<T>(&mut self, value: &T) -> Result<(), Error>

where T: Serialize + ?Sized,

Serialize a map value.

fn end(self) -> Result<Ok, Error>

Finish serializing a map.

fn serialize_entry<K, V>( &mut self, key: &K, value: &V, ) -> Result<(), Self::Error>

where K: Serialize + ?Sized, V: Serialize + ?Sized,

Serialize a map entry consisting of a key and a value.

impl<Ok, Error> SerializeSeq for Impossible<Ok, Error>

where Error: Error,

type Ok = Ok

Must match the Ok type of our Serializer.

type Error = Error

Must match the Error type of our Serializer.

fn serialize_element<T>(&mut self, value: &T) -> Result<(), Error>

where T: Serialize + ?Sized,

Serialize a sequence element.

fn end(self) -> Result<Ok, Error>

Finish serializing a sequence.

impl<Ok, Error> SerializeStruct for Impossible<Ok, Error>

where Error: Error,

type Ok = Ok

Must match the Ok type of our Serializer.

type Error = Error

Must match the Error type of our Serializer.

fn serialize_field<T>( &mut self, key: &'static str, value: &T, ) -> Result<(), Error>

where T: Serialize + ?Sized,

Serialize a struct field.

fn end(self) -> Result<Ok, Error>

Finish serializing a struct.

fn skip_field(&mut self, key: &'static str) -> Result<(), Self::Error>

Indicate that a struct field has been skipped.

impl<Ok, Error> SerializeStructVariant for Impossible<Ok, Error>

where Error: Error,

type Ok = Ok

Must match the Ok type of our Serializer.

type Error = Error

Must match the Error type of our Serializer.

fn serialize_field<T>( &mut self, key: &'static str, value: &T, ) -> Result<(), Error>

where T: Serialize + ?Sized,

Serialize a struct variant field.

fn end(self) -> Result<Ok, Error>

Finish serializing a struct variant.

fn skip_field(&mut self, key: &'static str) -> Result<(), Self::Error>

Indicate that a struct variant field has been skipped.

impl<Ok, Error> SerializeTuple for Impossible<Ok, Error>

where Error: Error,

type Ok = Ok

Must match the Ok type of our Serializer.

type Error = Error

Must match the Error type of our Serializer.

fn serialize_element<T>(&mut self, value: &T) -> Result<(), Error>

where T: Serialize + ?Sized,

Serialize a tuple element.

fn end(self) -> Result<Ok, Error>

Finish serializing a tuple.

impl<Ok, Error> SerializeTupleStruct for Impossible<Ok, Error>

where Error: Error,

type Ok = Ok

Must match the Ok type of our Serializer.

type Error = Error

Must match the Error type of our Serializer.

fn serialize_field<T>(&mut self, value: &T) -> Result<(), Error>

where T: Serialize + ?Sized,

Serialize a tuple struct field.

fn end(self) -> Result<Ok, Error>

Finish serializing a tuple struct.

impl<Ok, Error> SerializeTupleVariant for Impossible<Ok, Error>

where Error: Error,

type Ok = Ok

Must match the Ok type of our Serializer.

type Error = Error

Must match the Error type of our Serializer.

fn serialize_field<T>(&mut self, value: &T) -> Result<(), Error>

where T: Serialize + ?Sized,

Serialize a tuple variant field.

fn end(self) -> Result<Ok, Error>

Finish serializing a tuple variant.